The present invention relates generally to food waste disposers and, more particularly to a switch assembly for use in a food waste disposer.
Referring to FIG. 1, a portion of a conventional food waste disposer 10 is illustrated in a cross-sectional view. The conventional disposer 10 includes an upper food conveying section (not shown), a lower motor section 30, and a central grinding section 20 disposed between the food conveying section and the motor section 30. The food conveying section conveys food waste and water to the central grinding section 20. The central grinding section 20 includes a grinding plate 22 containing grinding lugs 24.
The motor section 30 includes an induction motor 40, enclosed within a motor housing 32 having an upper end frame 34 and a lower end frame 36. The motor 40 includes a stator 42 and a rotor 46. The stator 42 includes windings 44. The rotor 46 is disposed on a motor shaft 48. The motor 40 imparts rotational movement to the motor shaft 48, which turns the grinding plate 22 of the grinding section 20.
The motor shaft 48 includes a mechanical or centrifugal actuator 50 disposed adjacent the lower end frame 36. The centrifugal actuator 50 includes a body 52 attached to the motor shaft 48. Two weights 54 are pivotably connected to the body 52 and are biased together by one or more springs 56. The spring-loaded weights 54 move a movable plate 58 disposed about the motor shaft 48, as will be explained in more detail later.
A switch assembly 60 is attached to the lower end frame 36 adjacent the motor shaft 48 and centrifugal actuator 50. In particular, tabs 63 on the switch assembly 60 are press fit through apertures defined in the lower end frame 36. The switch assembly 60 includes an internal switch having a lever arm or blade 66 in contact with the movable plate 58 of the centrifugal actuator 50. When a certain rotational speed is reached by the motor 40, the spring-loaded weights 54 of the centrifugal actuator 50 move apart due to centrifugal force. The separation of the weights 54 causes the movable plate 58 to lift. In contact with the movable plate 58, the lever arm or blade 66 moves upward and an electrical connection is broken within the internal switch of the switch assembly 60. Typically, the electrical connection is broken when the motor reaches approximately 1500 to 1600 r.p.m. for 60 Hz. Motors or 1300 to 1400 r.p.m. for 50 Hz. motors and may occur within about 0.3 seconds from start-up. As will be discussed in more detail below, the internal switch, lever arm or blade 66, and centrifugal actuator 50 work in conjunction to control power to the windings 44 of the motor 40.
The switch assembly 60 houses an overload switch 70, which is typically a separately manufactured component. The overload switch 70 is used to cut power to the motor 40 under certain conditions. The overload switch 70 includes a reset button 72 disposed through an aperture 38 in the lower end frame 36. The reset button 72 allows a user to reset the overload switch 70 from outside the disposer 10.
Referring to FIGS. 2A and 2B, top views of two switch assemblies 60a and 60b according to the prior art are illustrated for use with the conventional disposer 10. In FIG. 2A, the switch assembly 60a represents a start switch used in a food waste disposer produced by. In-Sink-Erator(copyright), a division of Emerson Electric Co. In FIG. 2B, the switch assembly 60b represents a start switch produced by Whiterock Corporation of China.
The switch assembly 60a or 60b includes a body 62 that attaches to the lower end frame with retainers or tabs 63. The body 62 includes a contact switch 64a or 64b and houses the overload switch 70. The overload switch 70 may be, for example, a switch manufactured by Thermodisc Incorporated, a subsidiary of Emerson Electric Co., having a type 30M frame style. The overload switch 70 includes a terminal 81 and a connection point 85.
In the switch assembly 60a of FIG. 2A, the contact switch 64a includes a plastic ever arm 66a pivotally connected to the body 62 and biased open by a spring (not shown). As described above in FIG. 1, the plastic lever arm 66a moves with the movable plate 58 of the centrifugal actuator 50. A flexible, conductive blade 68a is connected to and movable with the lever arm 66a. The blade 68a is electrically connected to the terminals 82 and 84. In contrast to the switch assembly 60a of FIG. 2A, the lever arm 66b and flexible blade 68b of the contact switch 60b in FIG. 2B are an integral conductive piece. Despite this difference, the contact switch 64b operates in a substantially similar fashion to the contact switch 64a of FIG. 2A.
Referring to FIG. 2C, an electrical schematic of a switch assembly 60 according to the prior art such as assembly 60a or 60b, is illustrated. The switch assembly 60 is connected to leads L1-L3 from the motor of the disposer. The motor has run windings 44R and start windings 44S. The switch assembly 60 is also connected to leads L4-L5 from a power supply V.
The terminal 81 of the overload switch 70 connects in parallel to the windings 44S and 44R, and the connection point 85 connects to the power source V. Thus, the overload switch 70 can cut power to the windings 44S and 44R in case of a power overload. The terminal 82 is connected to the lead L2 from the run windings 44R. The terminal 83 is connected to the lead L3 from the start windings 44S. The terminal 84 is connected to the lead L4 from the power source V.
The contact switch 64 of the switch assembly 60 is used to control activation of the start windings 44S. At initial start-up of the motor 40, the contact switch 64 is closed so that the start and run windings 44S and 44R are both engaged. The start windings 44S are initially used in combination with the run windings 44R to overcome inertial forces of the rotor, shaft, and grinding plate of the disposer, in addition to other forces. After a certain point and in response to movement of the movable plate 58 of the centrifugal actuator 50, the contact switch 64 interrupts electrical connection between the power source V connected to terminal 84 and the start windings 44S connected to terminal 83, effectively shutting off the start windings 44S.
Although the switch assemblies 60a and 60b of FIGS. 2A and 2B operate efficiently and effectively, manufacturers continually strive to improve the efficiency of, and hence reduce the cost of, the manufacture and assembly of such switches and of the disposers in which they are contained. Unfortunately, the prior art switch assemblies have some drawbacks, which prevent these goals from being reached.
For example, the switch assemblies 60a and 60b according to the prior art are relatively difficult to install in the disposer 10. As noted above in FIG. 1, the switch assembly 60a or 60b includes tabs 63 that press fit into slots defined in the lower end frame 36. The overload switch 70 includes a reset button 72 that extends from the bottom of the switch assembly 60a or 60b and is disposed through the hole 38 in the lower end frame 36. During assembly, an operator manually positions the overload switch 70 within the housing 62 before attaching the assembly 60a or 60b to the lower end frame 36. However, the switch assembly 60a or 60b does not positively retain the overload switch 70. Consequently, the operator must hold the overload switch 70 in the assembly 60a or 60b while simultaneously pushing the tabs 63 into the slots defined in the lower end frame 36 and disposing the reset button 72 in the hole 38. Thus, the attachment of the assembly 60a or 60b to the lower end frame 36 requires manual dexterity from the operators, making the assembly process difficult.
In another drawback, the connection of leads to the switch assembly 60a or 60b offers further challenges to the assembly of the disposer. As shown in FIG. 2C, the switch assembly 60a or 60b has five terminals (81-85) that must be connected to the leads L1-L5 from the power source and motor. An operator typically performs some of these connections manually by press fitting a terminal connector connected to each lead onto the relevant terminal.
For example, for the switch 60a depicted in FIG. 2A, the terminals 81-83 extend in three different directions. The terminals 81-83 receive separate terminal connectors 91-93 connected to leads L1-L3 in three mating operations. In general, there is no guidance or built-in system for determining or indicating what lead attaches to which terminal. Consequently, the possibility of incorrectly wiring the leads to the switch assembly 60a is increased. Furthermore, the operator must attach each lead one at a time. Such difficult or time-consuming operations complicate the assembly of the disposer. Moreover, the terminals 81-83 in the prior art configurations of FIGS. 2A and 2B appear on different sides of their switch assemblies, making automated assembly difficult
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
A switch assembly usable in a food waste disposer is disclosed having several improvements over the prior art. The switch assembly positively retains an overload switch, making assembly of the switch into the disposer easier. The switch assembly includes terminals, which attach to the start and run windings of the disposer. The terminals are arranged in a uniform direction along a single side of the switch assembly. This arrangement allows a single, integrated connector of winding leads to be easily connected to the switch assembly, facilitating assembly and reducing the possibility of incorrectly wiring the disposer during construction.